A 24-year-old man has been arrested on suspicion of abduction over the disappearance of Hull student Libby Squire, police say.
The suspect is being held after officers attended an address in the city on Wednesday night, where a car was photographed being towed away from the scene, Humberside Police said.
The address where the man was arrested is around half a mile from the University of Hull student's home.
A police spokeswoman said 21-year-old Ms Squire has still not been found, and that finding her remains a "top priority".
The force says it has received hundreds of calls in the last week.
She was reported missing in Hull in the early hours of Friday morning and an intensive search has been mounted by police and volunteers.
Detective Superintendent Matt Hutchinson said after the arrest on Thursday: "We are still treating Libby's disappearance as a missing person's inquiry.
"I have said previously that we are keeping an open mind as to her whereabouts and that is still very much the case."
He added: "During the course of our investigations we have spoken to a taxi driver and another motorist who stopped to help Libby on the night.
"I want to make it clear that these two individuals are not suspects in this enquiry.
"My officers have been and will continue to work around the clock in our search for Libby."
Police officers will hand out leaflets around the area of the university and speak to people to gather as much information as possible for the case.
Officers said a special "media van" with a large screen will be driven around at the same time displaying information to help find her.
Ms Squire has not been seen by friends since getting into a taxi outside the Welly nightclub in central Hull at 11pm on Thursday 31 January.
She had been dropped off in a cab near her home on Wellesley Avenue at around 11:29pm on Thursday.
Ms Squire was seen for the final time 10 minutes later on CCTV close to a bench on nearby Beverley Road, where a driver stopped to offer her help.
Officers have said the motorist has been in touch and "really helped out".
Humberside Police has confirmed that the man has been ruled out as a suspect.
A neighbour, who did not want to be named, said she had heard an "urgent, panicked scream" outside her house at around 12.30am on Friday.
The woman, who lives near Miss Squire's home, said the area is populated by students who make a lot of noise "any day of the week".
Police said they were "extremely concerned" for the University of Hull student's welfare and that her disappearance was "very out of character".
Her parents Russell and Lisa made an emotional plea for anyone with information to come forward on Monday.
Mrs Squire said: "Libby, my darling pie, we just want to know that you are safe.
"Please get in touch with us any way you can.
"The whole family is missing you, especially me and your dad, your sisters and your brother.
"I miss you so much it's breaking my heart not knowing where you are.
"I love you."
Specialist officers have been supporting Ms Squire's family throughout.
Ms Squire has two younger sisters and a younger brother who all live in High Wycombe.
Officers said they had a "number of leads" and revealed the coastguard and firefighters were searching around the River Hull on Sunday.
Police dogs have also been deployed to the area where Ms Squires was last spotted.
Around 200 students carried out a search of the university premises on Saturday afternoon.
More 70 police officers have been searching for her since Friday, with 200 trainee officers drafted in to help.
Humberside Police superintendent Simon Gawthorpe asked people to check their gardens and out-buildings in case Ms Squire took shelter there.
Officers said on Monday they found Ms Squire's mobile phone at her home, but it had not provided any information about where she went.